Train control



Nov. 20, 1928. 1,692,361

, w. w. WENHOLZ TRAIN CONTROL Filfid April 1924 2 Sheets-Sheet 1 E 4.. s U

Nov. 20, 1928.

w. w. WENHOLZ TRAIN CONTROL Filed April 1924 2 Sheets-Sheet 2 w v i k i F5 w v v y m 61 Kt In 16 O L *E O U a E 2 i Q. j

N A'AVA (u llV'VVV It '6 g cs *1 I E Q E N u m o o -ium --i q! Patented Nov. 20, 1928.

UNITED STATES PATENT OFFICE.

,WALTER W. WENHOLZ, OF ROCHESTER, NEW YORK, ASSIGNOR TO GENERAL RAILWAY SIGNAL COMPANY, 033 ROCHESTER, NEW YGRK.

TRAIN CONTROL.

Application filed April 7,

This invention relates to automatic train control systems for railroads and more particularly to systems of the type commonly known as a continuous inductive track circuit control system.

In one type of continuous inductive control systems to which this invention more particularly relates, alternating current is supplied to the track rails of each block, provided the next block in advance is not occupied, in such a way that this current flows like a track circuit currentin opposite directions in the track rails. This track phase, or loop circuit train control current, is detected by suitable receiving coils carried on the locomotive or other railway Vehicle in front of the first pair of wheels and axle above the track rails, amplitied, and used to control a suitable single phase relay or other electro-responsive device.

In this type of so-callcd single phase or two-position system, a stray current of the proper frequency and of sutlicient magnitude flowing in either track rail will cause. false energization of the car relay, and, likewise, unbalanced currents flowing in the same direction in the track rails are liable to cause false energizationot the car relay.

One of the principal objects of the present invention is to provide an arrangement and organization of parts in a continuous inductive control system of the single phase or two position type, in which the car apparatus is protec ed against false operation by stray currents in the track rails.

The means employed tor attaining this object, according to the present invention, attords an additional control or influence which is used to make a set-up on the locomotive, permitting it to travel 1n so-called unsignalled territory, that is, territory not equipped for train control purposes, such as sidings, yard limits, and the like.

Various detailed, features, objects and advantages of the invention will be pointed out as the description progresses.

In describing the invention, reference will be made to the accompanying drawing in which: Fig. 1 shows in a simplified and diagrammatic manner the trackway and car apparatus constitutin one specific embodiment of the invention, the parts being shown in a manner to facilitateexplanation and understanding of the essential characteristics and functions of the invention, rather than to show the particular organization and con- 1924. Serial No 704349.

yita-nce, the unsignalled territory is presumed to bea portion of track, such as through yards, which is not equipped for automatic train: control. It should be understood, of course, thatunsigna-lled or non-control territory is found at various places and under varying conditions in practice. Ordinarily, sidings are not equipped for the automatic control of trains thereon, and this is also true of yard limits, and sometimes terminals. Also, a branch line of the railroad may not be equipped for train control purposes, yet a locomotive fully equipped may run from the equipped territory on the main line on to the branch line. The so-called unsignalled territory may be provided with back circuits and block signals, but not equipped for train control purposes; or, this unsignalled territory may not have any block signals.

In the train control or equipped territory, the track rails 1 are divided by insulated joints 2 into blocks in the regular way, one block C, with the adjacent end of another block B being shown. These blocks may be provided with block signals, or the block signals may be omitted and reliance placed upon the cab signals. Semaphore signals S are shown convontionally, without attempting to illustrate their control circuits, which may be of any one of the well-known forms or types.

The equipment for each block in train control territory is ordinarily the same; and a description oi one will su'rlice for all. For

vmvenience, the corresponding parts of the differentparts of the various blocks are given the same reference numbers with distinctive exponents. Each block is provided with the usual normally closed direct current track circuit, comprising a track'relay 3 and a track battery l. In series with the track battery a transmission line T, energized from a suitable alternator G, preferably of commercial frequency, such as sixty cycles. The typical control circuits for each block in train control territory are shown for'the block B,

where the circuit for the primary of the cor-.

responding transformer 6 includes a front contact 7 of the track relay 3 of the next block in advance. Instead of the front contact 7 of a track relay, a circuit controller on the corresponding"signal S. may be used, or other forms of control provided, such thatthe primary of said transformer on open circuit when the block next in advance occupied. It will be observed that, while the train. is in a clear block (the next block in advance being unoccupied), alternating current from the transmission line T is supplied through the transformer 6 across the track rails at the exit endjof said clearblock; whereas in a caution block (a block in the rear of an occupied block) the primary of said transformer ison open circuit and there is no such alternating current flowing in the track rails.

' The locomotive or other railway vehicle is shown conventionally as comprising a pair of wheels and axle 8, which represent the first or leading pair of wheels and axle of the vehicle. Carried by the'vehicle over each of the track rails and in inductive relation thereto, is a receiver or pick-up coil R or R-1. These coils are of the usual construction, with or without iron cores. I These receiving coils R and R 1 are preferablytuned to resonance by condensers asshown, and the Voltage drop across these condensers is applied to the inis assumed to be atWo-elem'ent or polyphase' relay of the induction type, using either a vane or a rotor as the movable element and having its contact fingers fastened thereto 1 and biased to a neutral position by counterwclghts, or the like.

One such finger 9 for the relay MB is shown conventionally. One field coil or winding 10 of the relay MR is con- "nected to the output circuit ofthe amplifier iii; and the other field winding 11 of said relay is connected to the output circuit of the other amplifier A1.

For reasons well known by those skilled in the art, the movable when both fieldwindings 1011 are energized by alternating current of thesame frequency and having a predetermined phase relation; Since the voltages induced by the regulartrack phase, or loop circuit train control current in the track rails are in time phase, it is necessary to cause phase displacement of the currents produced by such induced voltage so that the relay MR, which is presumed to be one of the induction type,*may operate. Such relative phase displacement may be produced in various ways, by the tuning of the receiving coils themselves, by tuning or ad justments in the amplifiers, or by tuning or adjustments in the output circuits of the amplifiers connected to the field windings 1 0. and 11 of the relay In the form shown, is assumed that the receiving coils R and R-1 are both tuned to resonance, that there? little, if any, phasedisplacement in the an'iplifiers-A and A l themselves, and that the desired relative phase displacement is obtained by making the circuits for the field windings of the relay MR resistive and reactive. in the circuit of field winding 10, and an inductive ,reactance 13 in the circuit for th field windingll. H v v I The regular train control current flowing in opposite directions in the track rails in a clear block, which for a given instance may be assumed to have instantaneous directional flow as indicated. by the arrows a, induces voltages in the 'receivingcoils .R and R'1 of such polarity that, when amplified and displaced in phase, the currents in the, field windings 10 and 11 of the relay MB produce a torque tending'to shift the movable element of said relay and its contact fingers to one extreme position, called the normal or iclear position. Uponinterruption of this regular train controlcurrent, the movable element and contact fingers of the, relay MR shift to theneutral or deenergized position, since both field Windings10 and 11 are deenergized. Such flow "of traincontrol current is inter-, rupted in a caution block, as previously 9X- plaincd, and also in a block occupied by another train ahead, due to shunting action of j the wheels and axles of said forward train.

In short, the relay MRis energized normally in a clear block, and 1s deenergized n a cantion or danger block, the finger9 shlfting As shown, a resistance 12 is included from the full line position correspondingto;

a clear indication and to the neutral or vertical position corresponding to a caution or danger indication.

The 'relayMR. may be usedto control any suitable or desired formof automatic train control apparatus, controllable by two influences or controls, corresponding to said relay energized to its normal position and deenergized. TilGiIJtUQlZlCUlilI form of this train control apparatus forms no part of the present inventiomand it has been shown diagrammatically and designated K. One suitable form of such apparatus is shown in the patent to Simmen, No. 1,150,309, August 17, 1915. This train control apparatus K is nniintained energized and inactive except for a maximum speed limit, if such is used, so long as the con.- tact finger 9 of the car relay MB is in the normal position. Likewise, a clear or green lamp 9 in multiple with said apparatus K is energized and lighted so long as clear trafiic conditions prevail. When the train enters a caution block and the contact finger 9 ofthe car relay MR drops to the deenergized position, the green lamp 9 is extinguished, the

various other adjuncts and expedients may be utilized;

One 1mportant feature of this invention is the protection afforded against false operation of the car relay MR by stray currents in the track rails of the same frequency as the regular train control current. Such stray current may be falsely applied from the transmission line T itself, due to crosses, grounds and the like, or may come from some foreign sourceof the same frequency, or of a frequency so nearly like the train control frequency thatthe tuning and receiving coils and amplifiers are not sufficient to avoid op eration of the car relay for large values of stray current. Such stray currents ordinarily flow in either one rail alone, or in both rails equally or unequally, but in the same direction for any given instant. Ifthis stray current is 1110116 rail only, itWi-ll be evident that thecar relay MR Will not respond, because only one of its field windings is energized. If such stray current flows in both rails causing said rails to be of the same instantaneous polarity, and the frequency and magnitude of such current is likely to falsely energize the relay MR, such energization causes the relay to operate to its reverse position, since the instantaneous directions of how of the stray currents are assumed to be the same, Whereas the. receiving circuits are constructed or adjusted to energize the relay Milt normally, only if the instantaneous directions of flow of the currents in the rails are opposite, as indicated by the arrows at. Consequently, the relay MR will not be falsely energized to the normal clear position by any stray current inithe track rails,such as are at all likely to flow; and this relay will I be falsely operated to the clear position only in the remote contingency that thestray currents shall be. not only ofthe proper fre- .quency and of sufficient strength, but shall 1 also have opposite instantaneous directions of flow in the two track rails corres 'ionding to the flow of track phase or loop circuit cur.- rent.

In view of the foregoing, it Will be evident that if a condition is artificially created Where the instantaneous directions of flow of the currents in the track rails are the same, the car relay MR will be reversed. Thus, it is possible to obtain an additional control out of the car relay MR by artificially creating such current flow. This may be done by a loop with a sufficient amount of current so that, together with a number of turns, the regular train control or track phase current flowing has its magnetic fields thrown out of balance and given instantaneous magnetic polarities in the same direction. Another Way is to supply alternating current of the regular frequency to the track rails in multiple, either With or Without the regular track phase current.

This additional control may be utilized for various purposes. In this particular embodiment of the invention, such additional control is employed for obtaining a set-up on the locomotive to permit it to run in unsignalled or unequipped territory; 7 For this purpose, there is provided a normally deenergized stick relay NS on the locomotive, conventionally termed the NS or no-signal relay. This NS relay has a pick-up circuit as follows, commencing at B, contact finger 9 of relay ME in the reverse position, Wire i l, push button P Wires 15 and 16, relay NS, and Wire 17 to C. This NS relay has a stick circuit that may be traced as follows: commencing at B, contact finger 9 of the relay MB in the neutral or deenergized position, Wire 18, contact finger 19 of relayrNS, through its front contact, wires 20 and 16, relay NS and Wire 17 to C.

\Vhenever thecontact finger 9 of the relay MB is shifted to the reverse position by any one of the expedients above mentioned, and the push button P is closed, the pick-up circuit for the relay NS is established; and when saidcontact finger 9 drops to the deenergizet position, a stick circuit for said relay is es tablished. The relay NS is preferably made slow releasing, so as not to drop away during the interval between the opening of the reverse contact and the closing of the deenergized contact of the main car relay.

The relay NS When energized is assumed to provide the controls necessary to permit the locomotive to travel in unequipped territory. For instance, the train control apparatus K is' maintained energized, the caution or danger cab signal or indicator r, extinguished, even though the relay MR is deenergized due to the absence of train control current, and a distinctive indicator or cab signal NS is illuminated to advise the engineer the train is traveling in imequipped territory.

t Will be observed that the setup for un- 'ated Without automatic train control.

til tl'ie train actua-lly enters unsignalledter signalled territory is obtained by ten'iporarily reversingthe ear relay MRsjust prior to the entrance of the train into the unequipped territory, the engineer operating the push-button P, thereby picking up the NS relay, -Wl1lGl1 is stuck up when the main car relay MRv drops upon the entrance of the train into the unequipped territory and 1s maintamedenergized so long-as the tram travels 1n such unequipped territory. 'Upon entrance into signalled or equipped territory, a permanently active loop or track section may be employed to operate the-relay MB to its normal position, so as to deenergize the NS relay; or,

reliance may be placed uponthe fact that as soon as the train entersaclear block, the re lay MR is energized and for this reason the territory begins at theexit end of the block C, While the train is running in unequipped or unsignalled territory,the engineer is supposed to be responsibleforthe safety of the train, relying upon train orders,iblocksign-als (if these are used) or similar safe-guards, the same as trains are ordinarilybeing operritory, ho\vever, it is consideredthat the engmeeris JLlStlfiGCl 1n relying upon the automatic train control system, including the indications'of the cab signals. the regular train control current for the: block For this reason,

Q which is supplied from the transformer -6 at the-exit end'ofthis block, is preferably cut off if there is a train Within braking distance for the normal running speed'beyond V the exit endof the block C. As showmthe block C is preferably also made dependent )rimaryof"the transformer 6 for the block C is controlled" by a line relay LR," Whichhas its energizing circuit taken through front contacts of a track relay 3 for'the-track section D and. a trackrelay 3 for another track section'E immediately in advance ofthe'section D, the combined length of the track sections D and E being equal to or-greater than such breaking distance. In VlBW ofthis control, the engineer While running throughthe block C under a clear signal, mayassume that there is no train Within braking distance of the'end of train control territory. The indicationsof the signal S at the entrance tothe upon the line relay LR, so that this-signal indicates caution if there-isa train presentin track section D or E.

The track section D is'r'elatively short, say 100 feet or less, and is merely long enough to assure time forthe operation ofsetting up the unsignalled territory control upon a locomotive passing over this track section at speed. It will be obse'rvedthat the track =sec tion D is provided With a trackbattery 4: transformer 6 and track relay 3 the same as a block in regular .train control or signal territory, except lthatthe primary of the transformer 6 is connected directly across the transmission line T and is not .traflic con.- trolled. In other Words,the alternatingcurrent for train control purposes is always '75 present on the track-rails for the track sec- .tion D. l

As previously explained, the energization of the NS relay on the car isaccomplishedby reversing the instantaneous-relative directions of flow of the currents in thetrack rails. As shown, this is accomplished forthe track section D by a loop L. This loop L is made of Wire or cable, Well "insulated and suitably armoured and protected, andwas shown comprises two turns. Two sides-of this loop are disposed closely to one of the track rails (the upper track rail as shown), preferably by being secured to the Web of the rail under-' 'neath the head. The other .side of the -loopL is disposed at somedistancefromthe railroad track, far enough so that the magnetic field created by-current therein Will not mater ally influence the receiving coils R and R l. This loop L is so connected that-thei currents in the sides of the loop adjacent to one track rail Will have 'for a given instant adirection of flow or polarity, indicated by the arrows'b, opposite to the instantaneous directionof current flow in the adjacent track rail, indicated by the arrow a, supplied from the transformer 6 Since, this loop L isin series with the primary of thetransformer' 6 it is assuredthat, whenever-there is current-flowing in the track rails of the tracksectionD there Will be current-in this loop. As shown,- it is assumed that each turn of the loop L carries-as much current as each track rail-ofthe section 'D;'but it is obvious that a largeror smaller number oftu rns' may be used as desired, so long as the combined magnetic field's have the desired values and polarities. Of course, the

have the same phase relation.

instantaneous magnetic polarities reverse from that of the magnetic fields extending.

over the traokrails in regular train control territory. In regular equippedterritor-y, the currents in the twotrack rails, and-likewise the resultant magnetic fields over the two rails, are of opposite instantaneous polarity, as indicated by the arrows a. .In-the track section D; however, the current in the loop L,

indicated by the arrows'b fort-he instantdn currents in said loop and track railsshould question, over-balances the current a in the adjacent track rail, giving the resultant, so far as the receiver R is concerned, of current flowing in this track rail of the same instantaneous direction of flow as that flowing in the other track rail.

A similar reversing of relative instantaneous direction of flow of current in one of the rails for the track section D may be obtained by supplying current which fiows in the track rails of this section in multiple; and this may be easily accomplished by conn cting a balancing resistance 24: across the track rails at each end of this section and connecting their middle points to the transmission line through a suitable transformer 25, as shown in Fig. 2- of the drawings. Other ways of accomplishing the same result are possible, and may be suitable under some certain of the varying conditions encountered inpractice.

In disclosing the nature of this invention, attention has been primarily restricted to one specific form, which has also been illustrated in a simplified and diagrammatic manner. It should be understood, however, that the invention is not restricted to the particular construction and arrangement of parts and circuits shown and described, but is susceptible of considerable modification, adaptation and addition. I desire to have it understood, therefore, that I include within the scope of this invention all modifications and adaptations, in so far as they may fairly come within the scope of the appended claims, with the terms of these claims broadly interpreted in the light of the purposes and function herein explained.

What I claim is 1. A train control system of the continuous inductive control type for railroads'provided with blocks comprising, means associated with each block for impressing across the track rails at the exit end thereof an alternating current voltage only if the block next in advance is unoccupied, receiving coils on a vehicle in front of the first pair of wheels and axles thereof and disposed over the track rails in inductive relation thereto, a two-element relay of the induction type on the vehicle having its field windings connected separately to said receiving coils, and means for causing relative phase displacement of the currents of said field windings with respect to the induced voltage in the receiving coils.

2. In a train control system, the combination with tratiic controlled means for impressing an alternating current voltage/across the track rails, whereby current of opposite in stantaneous directional flow is present in the track rails in front of a railway vehicle, of a polyphase relay on the vehicle, amplifiers, and separate receiving coils on the vehicle, said relay being operated in one direction by said current of opposite instantaneous directional flow and in the reverse direction by currents flowing in the same direction at the same instant. p

3. Locomotive equipment for train control systems of the continuous inductive type comprising, receiving coils carried in front of the first pair of wheels and axle of the locomotive,

one over each track rail in inductive relation thereto, said receiving coils being magnetically separate, amplifiers having their input circuits connected to said coils, and a twoelement relay of the induction type having its field windings connected separately to the output circuits of said amplifiers, there being relative phase displacement of the currents in the field windings of said relay for voltages of the same time phase induced in the receiving coils'whereby to operate the said relay by current flowing in a single track circuit. V p

4:. In a train control system of the continuous inductive type,-a three-position alternating current relay on acar, and means including receiving elements disposed only in 'front of the first pair of wheels and axles of the car for operating said relay either to one or to the other of its energized positions depending upon whether the instantaneous directions of flow of the alternating currents in the two track rails are in the same direction in the two rails or the flow of current in one rail is in one direction and the flow of current in the other rail is in the opposite'direction at a given instant.

5. In a train control system of the two position continuous inductive type in combination with vehicle-carried means including a three-position relay of the two coil type on the vehicle, inductive influence receiving means disposed over each of the two track rails in front of the first axle of the vehicle one of which is connected to one coilof said relay and the other of which is connected to the other coil, said relay assumingan energized position only if both of said coils are energized by current,said relay also moving a Contact in one direction if the flow of currents in the coils have a certain directional relation andmoving the Contact in the opposite direction. if the relative flow of currents in the two coils is reversed; and of trackway means for causing the flow of train control current down one rail through the axles of said vehicle and back through the other rail only in the block ocriuipied by the vehicle i t a portion of the block in advance of said yo hirle and the nextblock in advance thereof are not occupied-by another train, said flow of current down one rail andba-ck through the other acting on said influence receiving means to cause said relay to assume a normal energized position, and means for restricting the movement of the train it saidrelay changes from its normal position.

6. in a train control system of the continuous inductive type, with separate receiv ing coils carriedo'n a railway vehicle in front of its first pair of Wheels and axle, one coil being disposed over each of the two track rails and in inductive relation thereto, electro-responsi've means on the vehicle connected to said coils, said electro-responsive means being' operated differently for different relative instantaneous directions of fiow of alternating current in but one track'w'ay circuit in the two track rails. f i c v 7. In a train controlsystem, the cornbination Witlia blockprovided with a track relay, of means for supplying analternating current voltage across the track rails at the exit end of said block, thereby causing a flow of alternating current in the track rails in opposite instantaneous directions in front of a vehicle in said block, and electro-respon'sive means on the vehicle energized to one position if such flow of alternating current only exists and to a different position if currents flowing in said track rails in the same direction at a given instant only exist.

8. In a train control system of the con tinuous inductive type, a pair of receiving coils carried on a vehicle in front of its first pair of wheels and axle and disposed in inductive relation separately to the track rails,

a polyphase relay on the vehicle, and separate amplifying means on the vehicle connecting said receiving coilsindependently to thefield windings'of said relayan'd producing in said fieldwindings amplified currents relatively displaced in phase for voltages of the same time-phase relation which are induced in said coils by flow of alternatlng current 1n the track rails whereby the polyphase relay is operable by current flowing through a single trackcircuit. I 9. Receiving equipment for continuous inductive train control systems, comprising two separate receiving coilson the vehicle in front otits first pair of wheels and axle, separate amplifiers connected to said coils, and a polyphase relay having its field windings coupled to the output circuits of said amplifiers, said relay assuming one energized position it current flowing in opposite directions in the track rails at a given instant only exists and assuming the otherenergized position it currents flowing in the track rails in the same direction only exist.

10.111 a train control system, for "ailways having territory equipped for train control 7 purposes and territory not equipped for train control purposes, the combination with car equipment comprising receivers carried only in front of the first pair or Wlieels'and axle, a three=position relay on the car, mea'ns for operating said relay to either its denergized position or. oneof its energized positions depending up n ti'afiic conditions while the car is traveling in eqiiipped territory, and means for operating said relay to its other energized position \i 'lienthe car enters unequipped territory. v V 1 v 11. Ina train. control system of the continuous inductlve t'ype, 1n combination, car

receiving apparatus including two separate receiving coils carried in 'l'ront of the first pair of wheels and axlein inductive relation to the track rails, separate amplifiersconnected to said coils, a polyphase relay coupled to the output circuits' of said amplifiers,

said relay assuming one energized position if currentflows in the track rails in opposite a the reverse energized position ifcu-rrents flow in thetrack rails in the same direction only at a, given instant and assuming. thedeenen gize'd positionit there is current flowing'only in one of the rails or there is no current flo'wr'ei'reiving coils, said relay assuming a no-r-' mal energized condition in response to voltages induced in said receiving coils by' current flowing in opposite directions adjacent said; coils and assuming a reverse energized directions only at a given instant, assuming condition for voltages in said receiving coils correspondingto the flow o t'currents in the same direction adjacent said coils. I

. 13. In a train control system, the combina tion with a car-carried three-positionpolyphase relay responsive distinctly to voltages induced by magnetic fields corresponding to the flow of instantaneous"alternating current in opposite dlrections 1n the traclrrails alone and t0 the flow of instantaneous alternating current in the same direction in the track rails alone, of means for supplying alternating current to the track ra ls flowing 1n oppo:

site directions at a given instant undersatfe traffic conditions only for operating said relay to one energized position, and means at predetermined points along the track constituting a current conducting path and when energized producing a magnetic field combined with the field produced such flow of current 'in' one oft-he track rails to give resultant magnetic fields corresponding to the flow of current in the same direction in the ftwo track rails at a given instant, whereby said relay is operated to a different, energized position. i

described, in combination with a car 'carried three-position polyphase relay, of me nson the car and onthe track cooper'ating'i nductively throu h an intervening air-gap atlal'l points in the travel otthe car in certain'te'rritory to cause said relay to assume one of I 1 i. Ina train control system of the type its energized. positions under favorable traftic conditions due only to the flow of alternating current in the track rails flowing in opposite directions at a given instant, said relay being caused to assume its other energizer position'in other territory by effects corresponding only to flow of alternating current in the track rails in the same direction at a given instant. r

15. In a train control system of the continuous inductive type, in combination with a car-carried three-position relay of the twoelement induction type, of cooperatingmeans on the car and on the tra-clrway acting inductively through an intervening air-gap to cause said relay to assume one or the other of its energized positions, depending alone upon the flow of alternating currents in the same direction in the two track rails at a given instant and alone on the flow of alternating current in opposite directions in the two track rails at a given instant, respectively. I

16. In a train control system of the continuous inductive type, receiving means on a vehicle including a three-position polyphase relay operated to one energized position by alternating current flowing track rails ahead of the vehicle in opposite directions in the two rails at a given instant, said relay not being operated to said energized position by'flow of stray currents in the same direction in the track rails nor by the flow of stray current in one rail only.

17. A system of the type described in combination with circuits on the trackwa-y including the track rails and energized so as to cause alternating current to flow in opposite directions in said rails at a given instant under safe trafiic conditions only, electro-r sponsive means on a vehicle controlled inductively through an intervening air-gap by the flow of current in said trackway circuits and operable to its clear condition only by such flow of current in opposite directions in the track rails, whereby said relay is not falsely operated to the clear condition by the flow of stray current in one track rail or by the flow of stray current in both of the track rails in the same direction.

18. A train control system of the continuous inductive single phase or two-position type comprising, a polyphase alternating current relay on the vehicle, means on the vehicle for causing said relay to assume the normal ener ized posit-ion in response to the flow of a single alternating current flowing down one rail and back through the other rail and for causing the relay to assume the other and reverse energized position in re sponse to the flow of alternating currents flowing down the two rails substantially in phase with each other, and which will allow the relay to assume its de-energized posi tion it there is an alternating current flowing in one rail only, and means for restricting the movement of the train when said relay assumes either the reverse or the de-energized position.

19. A train control system according to claim 18 adapted for use in systems wherein only part of theterritory is equipped for train control purposes further comprising, a non-control territory eiectro-responsive device which it in its active energized position permits the train to proceed even though the polyphase relay is (ls-energized and having a pickup circuit and a stick circuit, a push button which it depressed closes a break in said pick-up circuit, said pick-up circuit including contacts closed only when said polyphase relay is in its reverse energized position and said stick circuit including contacts closed only if said polyphase relay is d e-energized.

20. Car-carried apparatus for automatic train control systems of the single phase alternating current continuous inductive type comprising, a polyphase relay, means inductively associated with one oi the track rails on which the car travels connected to one element of the polyphase relay ineans inductively associated with the other track rail and connected to the other element of said relay, said two means and relay being so constructed and correlated that flow of alternating current in phase opposition in the two track rails causes said relay to assume one energized position and the flow of alternating currents substantially in time phase in the two track rails causes said relay to assume the reverse energized position, and means for restricting the movement of the train it said relay assumes the reversed or the de-energized position.

21. A train control system according to claim 20 adapted for use in system wherein only part of the territory is equipped for train control purposes further con'iprising, a non-control territory electro-responsive device which. if in its active energized position permits the train to proceed even though the polyphase relay is tie-energized and having a pick-up circuit and a stick circuit, a push button which if depressed closes a break in s id pick-up circuit, said pick-up circuit including contacts closed only when said poly phase relay is in its reverse energized position and said stick circuit including contacts closed only it said polyphase relayis deenergized.

22. In combination, a railway, a soiu'ce of alternating current at times connected across the track rails thereof, two train carried windings in inductive relation with the two track rails respectively, a train carried relay device comprising two coils, means i'er energizing one of said coils solely by one oi said windings and the other coil solely by the other of said windin said relay device also comprising a contact which is closed when said windings are energized by alternating current flowing through the track rails in series but not by alternating current flowing through the track railsin multiple or in one rail alone, and train governing mechanism controlled by said contact.

23. In combinatioma railway, a source of alternating current connected across the track rails thereof, two train carried windings in inductive relation with said two track rails respectively, a contact controlled solely by said two windings and closed when both windings are energized but not when either winding alone is ener i zed, and train governing mechanism controlled by said contact.

24. In combination, a railway, a source of alternating current connected across the track rails thereof, two train carried windings in inductive relation with said two tracks rails respectively, and train governing mechanism controlled solely by said windings and responsive to energiza-t-ion of both windings but not to energization of either winding alone.

25. In a train control system of the continuous inductive type, with separate receivng coils carried on a railway vehicle in front of its first pair of wheels and axle, one coil being disposed over each of the two track rails respectively and in inductive relation thereto, electro-responsive means on the re; lncle connected to said co ls, said GlGGtIO-TQ' sponsive means being operated differently forcurrent flowing in the same direction in carried alternating current relay having two windings controlled by the currents inthe two track rails respectivelywhereby the relay is energized in normal direction when current flows through the ralls 1n serles and in reverse direction when current flows through the rails'in multiple, and train carried governing mechanism controlled by said relay.

In testnnony whereofl aflix my signature.

'WALT nwl "W tNrI'O i I 

